Sunday

January 25, 2015

January 25, 2015

Posted by **vett** on Tuesday, May 31, 2011 at 9:59pm.

- math -
**MathMate**, Tuesday, May 31, 2011 at 10:15pmWe usually use Uppercase letters to represent angles, and lowercase for side lengths.

I resume the question as follows:

in abc, =60°,a=12, and b=5. find c.

We can solve this using the cosine rule:

c²=a²+b²-2abcos(C)

Substitute the numbers and take the square-root of c² to get c.

- math -
**Anonymous**, Tuesday, May 31, 2011 at 10:20pmUse law of cosines:

c^2 = a^2 + b^2 - 2*a*b*cos(C)

c^2 = 12^2 + 5^2 - 2 * 12 * 5 * cos(60°)

c^2 = 144 + 25 - 120*cos(60°)

c^2 = 169 - 120 * 0.5

c^2 = 169 - 60 = 109

c = sqrt(109) = 10.4403

**Answer this Question**

**Related Questions**

Math - 1. Find the value of Sin^-1(-1/2) a. -30 degrees b. 30 degrees c. 150 ...

Genius Math - Triangle ABC has AC=BC, angle ACB=96 degrees. D is a point in ABC ...

math - In triangle ABC, AB=2 square root 2, BC=8,angle ABC=45 degrees.Find area ...

Geometry - Please answer at least one . PLEASE 1. Triangle XYZ has a right ...

geometry - Find m<ABC if line BD is an angle bisector of angle ABC and m<...

Math Geometry - given triangle abc, measure of angle b= 120 degrees, ab= 6 units...

maths - ABC is an acute triangle with ∠BCA=35∘. Denote the ...

maths - ABC is an acute triangle with \angle BCA = 35 ^\circ. Denote the ...

Geometry - ABC is an acute triangle with \angle BCA = 35 ^\circ. Denote the ...

Trig functions and such - 1)Find the exact value of cot(-315) A)1 B)square root ...